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In this paper we review the effects of the provision of artificial sources of water on native flora and fauna in arid and semi-arid zones, with emphasis on Australia but drawing on information from other countries where possible. The effects of artificial sources of water are profound and are a rarely-cited aspect of change in arid and semi-acid zone rangelands. Direct effects of artificial sources of water include: (1) the development of wetlands that support native plants and animals; (2) the expansion of geographic range and increased abundance of native animals which need to drink regularly; and (3) the possible expansion of breeding ranges of invertebrates that require water for some stage of their life cycle. The major indirect effects of artificial sources of water are as a source of drinking water for domestic stock, and native and feral mammalian herbivores, and so they provide a focus for grazing. Recorded changes in vegetation in response to grazing around artificial sources of water are: (1) the development of a zone of extreme degradation around the water (up to 0.5 km) where soil crust is broken, erosion is high and unpalatable plants dominate; (2) an increase in the number of unpalatable perennial shrubs beyond the extreme degradation zone, particularly in semi-arid woodland and arid shrubland habitats; and (3) a decrease in abundance of palatable native perennial grasses due to selective grazing. Effects of grazing on native fauna are poorly documented but published accounts include: (1) a possible contribution to the recent extinction of some medium-sized native mammals in Australia, also assisted by those introduced predators which rely on drinking water; (2) the displacement of some ground-dwelling bird species from regions heavily developed for pastoralism, and geographic range reductions for many other species of birds; and (3) changes to the distribution and abundance of invertebrates such as grasshoppers, ants and collembolans. Artificial sources of water may also indirectly affect native wildlife by acting as foci for the activities of native and introduced predators. (C) 1999 Academic Press.